The Cardinals placed Brad Penny on the disabled list on Saturday due to a strained right lat muscle, but general manager John Mozeliak expressed optimism that Penny will only be out for the minimum 15 days. St. Louis recalled right-handed pitcher P.J. Walters from Triple-A Memphis to take Penny’s roster spot.

Penny received an anti-inflammatory shot in the area of the injury on Saturday morning. The club hopes he can resume throwing in approximately 7-10 days, and be back on the mound in a game in 15 days.

“Right now we think it’ll be a minimal stay on the 15-day,” Mozeliak said on Saturday morning. “That’s what we’re hopeful of.”

Penny said he first felt the injury after he pitched last weekend in Cincinnati, and that he aggravated it while pitching on Friday night against the Angels.

Note of the night: It’s more Brad Penny, of course. I have 900 words or so on the topic up on the site now, but there’s still more to go into.

Most notably, there’s the fact that Penny felt something after his last start and didn’t notify the club. Those of you who watched the postgame probably noticed that TLR said that his mood “stinks.” And when asked if Penny’s injury was the cause, he said, “Yeah, that’s part of it.”

And while the manager didn’t elaborate beyond that, it can’t have sat well that Penny pitched while knowing that he had something amiss physically.

“The first day after Cincinnati, it didn’t feel that good,” Penny said. “The second day, it felt a little better. It was getting better and better, and I didn’t feel it at all in the bullpen [on Friday evening].”

Penny threw a side session between starts, and said he felt the injury “a little bit” at that time.

Other Penny-related stuff: According to my friend Will Carroll, Baseball Prospectus’ injury guy, 4-6 weeks is a fairly reasonable time frame for a pitcher with a lat injury. … P.J. Walters, who is en route from California as I write this, was absolutely lights-out in three starts at Memphis this year, allowing one earned run in 18 2/3 innings with 23 strikeouts and three walks.

Stat of the day: The Cardinals’ slugging percentage, as a TEAM, went up by seven full points on Friday night, from .400 to .407.

Fun with double situational splits: David Freese is batting .464 (13-for-28) with a .500 on-base percentage and a .929 slugging percentage in day games at home this year, and against lefties at home his line is .444/.524/.556.

Cardinals general manager John Mozeliak confirmed on Friday night that right-hander P.J. Walters is on his way to St. Louis to join the team on Saturday afternoon. Mozeliak said that the club has not yet determined who will be placed on the disabled list to accommodate Walters.

The options are starter Brad Penny, who left Friday’s win over the Angels with a right lat strain, and reliever Blake Hawksworth, who is sidelined due to a sore right groin. The club will determine which player will be shelved on Saturday morning after further evaluation of the two injured players’ situation.

Saturday would be Walters’ day to pitch Triple-A Memphis, which is playing at Sacramento this weekend. So he will be available to pitch multiple innings in relief over the weekend. Any decisions beyond that remain a bit hazy. Walters could take Penny’s next turn in the rotation, or the Cardinals could look to Adam Ottavino to take that job.

Note of the night: Brendan Ryan actually had some fun on Thursday. He got a hit, drew a walk, played solid defense and smiled on the field. All of those things count as progress for the Cardinals infielder.

Still, he’s not giving up on ways to try to break his early-season funk. He said he took “about 100″ swings left-handed in the batting cage on Wednesday — not because he’s trying to switch-hit, but just because, well, because he’s Brendan Ryan.

And, in response to a clamor from fans and teammates — he’s bringing back the mustache. Ryan was wearing his “Respect the Redbird ‘Stache” t-shirt in the clubhouse on Thursday afternoon, and showing the first signs of growth on his upper lip — though he joked that the full effect may not be seen for another month.

“I’m doing anything possible to make some good things happen, so whatever it takes,” Ryan told reporters after Thursday’s game.

Stat of the day: Matt Holliday has not hit a home run at home this year and is slugging .323 at Busch Stadium.

Fun with double situational splits: Felipe Lopez is 2-for-15 (.133) against right-handed pitchers at home this year, though he does have four walks for a .316 on-base percentage.

The situation: Top of the sixth, 0-0 game. 7-8-9 in the Marlins order coming to the plate.

The decision: TLR goes to Blake Hawksworth to pitch the sixth.

The outcome: Hawksworth has a rough outing, allowing two singles, walking the pitcher (who was trying to sacrifice), and then a sacrifice and an RBI single in the sixth, before permitting a pair of homers in the seventh.

The analysis: At this point in the game, TLR understandably wants to go to a pitcher who can get more than a batter or two, and ideally more than an inning. It’s the role that two years ago, Kyle McClellan had — get a close game from the sixth to the eighth — and it can be a very important and valuable role.

The inning started with two right-handed hitters, so the two lefties were both out, and it’s obviously not going to be Ryan Franklin or McClellan at this point in the game. That leaves three options: Hawksworth, Mitchell Boggs and Jason Motte.

Motte has moved up the food chain a bit, and they also like having his strikeout ability to put out fires with runners on base. So to narrow it further, it’s pretty strictly a question of Boggs vs. Hawksworth at this point.

And the thing is, if they do take the lead, there’s a good chance the other one won’t pitch. Ideally, one of the two righties gets you at least into the seventh before you hand off to the guys who get you home.

Hawksworth somewhat irritatedly dismissed the notion that he’s “struggling,” pointing to his 2.35 ERA entering the game, but he’s been much less effective in May than he was in April. Boggs, meanwhile, had been excellent over his previous 11 appearances — 11 2/3 innings, 12 Ks, 5 BB, 3 runs.

And while Hawksworth is nominally the long man on the staff, Boggs has gone 2+ innings as many times (three) as Hawksworth has this year. They were both rested and fully available, as was evidenced when Boggs pitched the final two innings.

The comment: “I’m going inning to inning. Go inning to inning and see how he’s throwing.” — La Russa

My verdict: I understand the idea that every pitcher in the bullpen needs to be able to get big outs, because at some point they’re all going to be asked to. I understand the hesitance to name Hawksworth, or any pitcher, the long man or the mopup man.

But the results don’t lie, and Hawksworth is having a tough May while Boggs is coming on strong. Those are high-leverage innings, even though it’s the sixth, and you need to go to the guy with the best chance of keeping the tie game intact. From the two viable choices, that guy is Boggs right now.

Moreover, to at least some degree, Hawskworth is on the roster in order to pitch those long innings in ugly games. Somebody has to be that guy. Somebody has to be the pitcher that you don’t mind using for 3-4 innings in a blowout, so that the next day, when it’s a tight game, you can use someone

As I’ve written in previous editions of this feature, they didn’t lose because of this decision. They lost because they scored two runs, and in some small part because they had to ask for four innings from the relief corps. But it’s definitely my opinion that going to Boggs in the sixth would have increased the chances of winning this game.

Note of the night: The Cardinals announced after tonight’s game that outfielder Shane Robinson will undergo season-ending surgery on his left shoulder.

Robinson, 25, separated his shoulder while sliding into second base in a May 8 game at Round Rock. He made his Major League debut last year, batting .240 with a .231 on-base percentage and .280 slugging percentage in 26 plate appearances.

A speedy right-handed hitter, Robinson had put up a .279/.330/.407 line at Memphis this season.

Dr. George Paletta, the Cardinals’ head team physician, will perform the operation.

Stat of the day: The Cardinals have scored 65 runs in 18 May games, for an average of 3.61 runs per game. That’s 13th in the National League. They’re slugging .372 as a team for the month, and their nine home runs in May are tied for 14th in the league.

Fun with double situational splits: Matt Holliday is batting .174 in day games at home this year, with a .296 on-base percentage and a .261 slugging percentage.

And, finally, the playlist:

I’m still on a Stones kick, and tonight’s playlist is even lazier than last night’s. It also consists of equally fantastic tunes. It’s the great side one of the great “Get Yer Ya-Ya’s Out”

Meta

The following are trademarks or service marks of Major League Baseball entities and may be used only with permission of Major League Baseball Properties, Inc. or the relevant Major League Baseball entity: Major League, Major League Baseball, MLB, the silhouetted batter logo, World Series, National League, American League, Division Series, League Championship Series, All-Star Game, and the names, nicknames, logos, uniform designs, color combinations, and slogans designating the Major League Baseball clubs and entities, and their respective mascots, events and exhibitions.